The present invention relates to the error processing of a data error which occurs in the recording or playing back of picture data and code data onto and from an optical disk in a picture data record/playback system for recording picture data on a document; e.g., for recording picture data onto an optical disk and playing it back therefrom, as required.
In recent years, a tremendous amount of documents have been produced, in offices and factories, for example. For the electronic processing of such documents, a picture data record/playback system has been developed. In this system, the picture data on a document is optically read out by a two dimensional scanning method. The picture data thus read out is sequentially stored in a recording medium, such as an optical disk. The retrieval data for individual picture data is stored in a recording medium, such as a floppy disk. In reading out the desired picture data from the optical disk, a retrieval code associated with the desired picture data is input into the system. The data read out is visualized by a CRT device or a printer.
This type system is defective, however, in that the optical disk used is physically damaged by dust particles attached thereto or being deposited thereon when it is handled. When damaged, the damaged optical disk incorrectly plays back the picture data from a damaged portion of the optical disk.
Generally, the picture data has high redundancy. Accordingly, the picture data may be recorded on the optical disk, allowing for the errors contained therein, to some extent. Code data such as character text and retrieval words has a much lower quantity than picture data. Therefore, for the code data, the probability of the error occurrence must be extremely low. As for the data amount of both the picture data and the code data, one page of a document of A4 size needs a memory capacity of approximately 600 KB in case that the picture data in the one page document is treated as binary picture with a 0.1 mm resolution. A character test (in Japanese) having picture data of 60 characters.times.50 lines on one page of an A4 size document may be expressed by 6 kilo bytes (5 KB), at most.
Errors contained in two types of data with different error tolerances must be appropriately processed. In so far as we know, however, data processors with such error correction ability have not yet been developed.